Technical Field
The present invention relates to a method of photooxygenating furfural using a photooxygenating system to produce a furanone compound.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
Ecological sustainability concern and surging crude oil prices have amplified industrial interest for renewable biomass resources [K. Tekin, S. Karagöz, S. Bektaç, Hydrothermal conversion of woody biomass with disodium octaborate tetrahydrate and boric acid, Ind. Crops Prod. 49 (2013) 334-340]. Of the various biomasses with abundant and renewable energy sources, rice husk is not only a cheap potential source of energy, but also a value-added by-product [L. T. Vlaev, I. G. Markovska, L. A. Lyubchev, Non-isothermal kinetics of pyrolysis of rice husk, Thermochim. Acta 406 (2003) 1-7]. Its annual worldwide output is in million tons [Q. Lu, X. Yang, X. Zhu, Analysis on chemical and physical properties of bio-oil pyrolyzed from rice husk, J. Anal. Appl. Pyrolysis 82 (2008) 191-198], and its major components are hemicellulose (19%), cellulose (40%), silica (17%) and lignin (16%) [R. Suxia, X. Haiyan, Z. Jinling, L. Shunqing, H. Xiaofeng, L. Tingzhou, Furfural production from rice husk using sulfuric acid and a solid acid catalyst through a two-stage process, Carbohydr. Res. 359 (2012) 1-6]. Agricultural waste-based lignocellulosic materials rich in pentosans have generally been preferred for producing value-added chemicals [O. Yemiç, G. Mazza, Acid-catalyzed conversion of xylose, xylan and straw into furfural by microwave-assisted reaction, Bioresour. Technol. 102 (2011) 7371-7378] since they are homogeneous and readily available in large quantities from cheap sources [I. Harry, H. Ibrahim, R. Thring, R. Idem, Catalytic subcritical water liquefaction of flax straw for high yield of furfural, Biomass Bioenergy 71 (2014) 381-393]. Biomass resources are a perfect choice to replace the petroleum feedstock [A. J. Ragauskas, C. K. Williams, B. H. Davison, G. Britovsek, J. Cairney, C. A. Eckert, et al., The path forward for biofuels and biomaterials, Science 311 (2006) 484-489]. They are even considered viable options for improving energy security and reducing greenhouse-gas emissions thus addressing the recurrent treatment challenges of waste streams from process plants [C. Di Blasi, C. Branca, A. Galgano, Biomass screening for the production of furfural via thermal decomposition, Ind. Eng. Chem. Res. 49 (2010) 2658-2671]. However, their effective utilization is limited by the quest in developing inexpensive processing methods that are capable of transforming the abundantly available carbohydrate moieties into value-added chemicals [J. N. Chheda, Y. Roman-Leshkov, J. A. Dumesic, Production of 5-hydroxymethylfurfural and furfural by dehydration of biomass-derived mono- and poly-saccharides, Green Chem. 9 (2007) 342]. Recently, furfural has received renewed attention as a potential renewable platform for the production of biochemicals and biofuels [C. M. Cai, T. Zhang, R. Kumar, C. E. Wyman, Integrated furfural production as a renewable fuel and chemical platform from lignocellulosic biomass, J. Chem. Technol. Biotechnol. 89 (2014) 2-10]. Furfural (2-furaldehyde) is a versatile furan platform comprised of a hetero-aromatic furan ring and an aldehyde group and is reported to be the sole precursor for compounds containing furoyl (furoyl glycine and 2-furoylchloride), furyl (furanones and furans), and furfurylidene radicals [O. Yemiç, G. Mazza, Acid-catalyzed conversion of xylose, xylan and straw into furfural by microwave-assisted reaction, Bioresour. Technol. 102 (2011) 7371-7378]. It is asserted to be among the top 30 high-value bio-based chemicals [T. Werpy, G. Petersen, Top Value Added Chemicals from Biomass Volume I—Results of Screening for Potential Candidates from Sugars and Synthesis Gas Top Value Added Chemicals From Biomass Volume I: Results of Screening for Potential Candidates, US Department of Energy, Technical report, DOE/GO-102004-1992 August 2004], and its demand is greatly felt in fields such as petrochemical refining, agrochemical, pharmaceutical and plastics industries [A. S. Dias, S. Lima, M. Pillinger, A. A. Valente, Acidic cesium salts of 12-tungstophosphoric acid as catalysts for the dehydration of xylose into furfural, Carbohydr. Res. 341 (2006) 2946-2953].
Furfural production involves both acidic hydrolysis and dehydration through either one or two stage process using either one or multiple reactors [R. Suxia, X. Haiyan, Z. Jinling, L. Shunqing, H. Xiaofeng, L. Tingzhou, Furfural production from rice husk using sulfuric acid and a solid acid catalyst through a two-stage process, Carbohydr. Res. 359 (2012) 1-6; O. Yemiç, G. Mazza, Acid-catalyzed conversion of xylose, xylan and straw into furfural by microwave-assisted reaction, Bioresour. Technol. 102 (2011) 7371-7378] as shown in FIG. 2 [K. Yan, G. Wu, T. Lafleur, C. Jarvis, Production, properties and catalytic hydrogenation of furfural to fuel additives and value-added chemicals, Renew. Sustain. Energy Rev. 38 (2014) 663-676]. In most research reports, a two-stage process is utilized since it generates higher furfural yield [V. Punsuvon, P. Vaithanomsat, K. Iiyama, Simultaneous production of a-cellulose and furfural from bagasse by steam explosion pretreatment, Maejo Int. J. Sci. Tech 2 (2008) 182-191].
The currently used batch and continuous furfural production processes are energy intensive, expensive, environmentally unfriendly and cause acid wastes [O. Yemiç, G. Mazza, Acid-catalyzed conversion of xylose, xylan and straw into furfural by microwave-assisted reaction, Bioresour. Technol. 102 (2011) 7371-7378]. Hence, the recent trend in furfural research is geared towards novel production processes that are both inexpensive and environmentally appealing. The techniques of supercritical fluid extraction [W. Sangarunlert, P. Piumsomboon, S. Ngamprasertsith, Furfural production by acid hydrolysis and supercritical carbon dioxide extraction from rice husk, Korean J. Chem. Eng. 24 (2007) 936-941], pressurized solvent extraction [H. K. Ong, M. Sashikala, Identification of furfural synthesized from pentosan in rice husk, J. Trop. Agric. Food Sci. 35 (2007) 305-312] and microwave-assisted extraction method [O. Yemiç, G. Mazza, Acid-catalyzed conversion of xylose, xylan and straw into furfural by microwave-assisted reaction, Bioresour. Technol. 102 (2011) 7371-7378] have been accepted as novel methods in furfural production.
Conversely, the use of abundant sunlight as a clean source of energy to initiate chemical transformations has attracted the attention of synthetic organic photochemists, since a variety of photoreactions high in selectivity, chemical yields and photon efficiencies are generated [M. Oelgemöller, O. Shvydkiv, Recent advances in microflow photochemistry, Molecules 16 (2011) 7522-7550]. Moreover, sunlight is a cheap, environmental friendly, plentiful and continuous renewable source of clean energy. However, despite these significant merits, organic synthesis still remains highly resource- and labor-intensive [P. T. Anastas, M. M. Kirchhoff, Origins, current status, and future challenges of green chemistry, Acc. Chem. Res. 35 (2002) 686-694]. Recently, microphotochemistry has been utilized in synthetic organic chemistry since it combines the advantages of miniaturized microflow systems with organic photochemistry [D. Webb, T. F. Jamison, Continuous flow multi-step organic synthesis, Chem. Sci. 1 (2010) 675]. The continuous removal of the product mixture from the irradiated area reduces secondary photoreactions, whereas the thin reaction channels enable efficient penetration of light through the reaction mixture (as dictated by the Beer-Lambert law) [S. Aida, K. Terao, Y. Nishiyama, K. Kakiuchi, M. Oelgemöller, Microflow photochemistry—a reactor comparison study using the photochemical synthesis of terebic acid as a model reaction, Tetrahedron Lett. 53 (2012), 5578-5581].
In addition, organic dyes as the photosensitizer in photochemical reactions are cheap, easy to prepare, more environmentally friendly and present a practical alternative to inorganic photocatalysts [H. Liu, W. Feng, C. W. Kee, Y. Zhao, D. Leow, Y. Pan, et al., Organic dye photocatalyzed a-oxyamination through irradiation with visible light, Green Chem. 12 (2010) 953]. The application of light-induced reactions in continuous flow microreactors combines the advantages of microreactor technology with sunlight photons as clean and traceless reagents [S. Hejda, M. Drhova, J. Kristal, D. Buzek, P. Krystynik, P. Kluson, Microreactor as efficient tool for light induced oxidation reactions, Chem. Eng. J. 255 (2014) 178-184]. In addition, microreactors offer higher spatial illumination homogeneity and better light penetration throughout the entire reactor [T. Aillet, K. Loubiere, O. Dechy-Cabaret, L. Prat, Photochemical synthesis of a cage compound in a microreactor: rigorous comparison with a batch photoreactor, Chem. Eng. Process.: Process Intensif. 64 (2013) 38-47].
In view of the forgoing, one objective of the present invention is to provide a method of synthesizing a furanone compound (e.g., 5-hydroxy-2-(5H)-furanone) by photooxygenating furfural, which is extracted from rice husk, using an in-house fabricated quartz capillary microreactor (0.5 mm diameter and 3 m length).